The present invention relates to refrigerated enclosures and more particularly to refrigerated trucks, trailers, containers, railroad cars and the like.
Frozen and perishable products are transported in enclosures or units such as refrigerated trailers, trucks, railroad cars, containers and the like. Generally, self-contained forced air refrigeration systems maintain the desired temperature within the unit To limit localized hot or cold spots, a relatively uniform flow of conditioned air around the cargo or load is necessary Improper air flow permits thawing of product during warm weather and freezing of the product during cold weather. In fact, the principal cause of product damage is such thawing and freezing. Various constructions have been proposed to achieve the desired flow pattern. For example, the unit may be lined with ribbed panels and a ribbed floor which define air ducts and space the cargo or load from the sides and bottom of the enclosure. Examples of trailers and the like employing permanent ribbed panels or sidewalls may be found in U.S. Pat. No. 2,289,489 entitled RAILROAD CAR INSIDE LINE and issued on Jul. 14, 1942 to Ennis; U.S. Pat. No. 2,923,384 entitled FLOOR CONSTRUCTION FOR REFRIGERATED ROADWAY VEHICLES and issued on Feb. 2, 1960 to Black; U.S. Pat. No. 3,308,738 entitled VENTILATING RIB PANELS and issued on Mar. 14, 1967 to Heimann; and U.S. Pat. No. 3,673,812 entitled BOXED PRODUCE LOAD and issued on Jul. 4, 1972 to Pierce.
Even though ribbed siding and interior liners are available, the vast majority of units for the refrigeration transportation industry are manufactured with smooth interior sidewalls. The increased manufacturing cost of the ribbed panels or interior is typically not justified in view of the substantially higher maintenance costs, repair costs and downtime.
A need exists for a transportation unit or enclosure which readily accommodates perishable or frozen products and provides the required channels or passages for proper air circulation yet permits efficient transport of dry freight and eliminates the high cost and maintenance problems heretofore experienced.